/*
 * [The "BSD licence"]
 * Copyright (c) 2012 Dandelion
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * 1. Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 * 3. Neither the name of Dandelion nor the names of its contributors 
 * may be used to endorse or promote products derived from this software 
 * without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package com.github.dandelion.datatables.jsp.tag;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;

import com.github.dandelion.core.utils.EnumUtils;
import com.github.dandelion.core.utils.StringUtils;
import com.github.dandelion.datatables.core.callback.Callback;
import com.github.dandelion.datatables.core.callback.CallbackType;
import com.github.dandelion.datatables.core.util.ProcessorUtils;

/**
 * <p>
 * JSP tag used to add a DataTables callback.
 * <p>
 * Note that this tag will be processed only once, at the first iteration.
 * 
 * <p>
 * Example usage:
 * 
 * <pre>
 * &lt;script>
 *    function myInitCallback(oSettings, json) {
 *      // some stuff
 *    }
 * &lt;/script>
 * ...
 * &lt;datatables:table id="myTableId" data="${persons}">
 *    &lt;datatables:column title="Id" property="id" />
 *    &lt;datatables:column title="Firstname" property="firstName" />
 *    &lt;datatables:column title="LastName" property="lastName" />
 *    &lt;datatables:column title="City" property="address.town.name" />
 *    &lt;datatables:column title="Mail" property="mail" />
 *    &lt;datatables:callback type="init" function="myInitCallback" />
 * &lt;/datatables:table>
 * </pre>
 * 
 * @author Thibault Duchateau
 * @since 0.8.9
 */
public class CallbackTag extends TagSupport {

	private static final long serialVersionUID = -3453884184847355817L;

	/**
	 * Tag attributes
	 */
	// Type of the callback
	private String type;

	// Name of the function
	private String function;

	/**
	 * Internal attributes
	 */
	private HttpServletRequest request;
	
	/**
	 * {@inheritDoc}
	 */
	public int doStartTag() throws JspException {

		request = (HttpServletRequest) pageContext.getRequest();
		TableTag parent = (TableTag) findAncestorWithClass(this, TableTag.class);
		if (parent != null) {
			return SKIP_BODY;
		}

		throw new JspException("The tag 'callback' must be inside the 'table' tag.");
	}

	/**
	 * {@inheritDoc}
	 */
	public int doEndTag() throws JspException {

		AbstractTableTag parent = (AbstractTableTag) findAncestorWithClass(this, AbstractTableTag.class);

		// The tag is evaluated only once, at the first iteration
		if (parent.isFirstIteration()) {

			CallbackType callbackType = null;
			try {
				callbackType = CallbackType.valueOf(this.type.toUpperCase().trim());
			}
			catch (IllegalArgumentException e) {
				StringBuilder sb = new StringBuilder();
				sb.append("'");
				sb.append(this.type);
				sb.append("' is not a valid callback type. Possible values are: ");
				sb.append(EnumUtils.printPossibleValuesOf(CallbackType.class));
				throw new JspException(sb.toString());
			}

			function = ProcessorUtils.getValueAfterProcessingBundles(function, request);
			
			// The callback has already been registered
			if (parent.getTable().getTableConfiguration().hasCallback(callbackType)) {
				parent.getTable()
						.getTableConfiguration()
						.getCallback(callbackType)
						.appendCode(
								(callbackType.hasReturn() ? "return " : "") + function + "("
										+ StringUtils.join(callbackType.getArgs(), ",") + ");");
			}
			// The callback hasn't been registered yet
			else {
				parent.getTable()
						.getTableConfiguration()
						.registerCallback(
								new Callback(callbackType, (callbackType.hasReturn() ? "return " : "") + function + "("
										+ StringUtils.join(callbackType.getArgs(), ",") + ");"));
			}
		}

		return EVAL_PAGE;
	}

	public void setType(String type) {
		this.type = type;
	}

	public void setFunction(String function) {
		this.function = function;
	}
}